The present invention relates to self-extinguishing polymer compositions which are suitable for fields such as wire coating, extrusion molding of pipes, and injection molding of the casing of domestic appliances and wire connectors, and which are much practicable from the viewpoint of the mechnical properties.
In recent years, demands for the flameproofing of resin materials used as wire cables have greatly increased.
In one method of flameproofing thermoplastic resins or elastomers, antimony oxide and a halide are blended, but the self-extinguishing compositions obtained by this method generate toxic gases during a fire.
Therefore, attention is being paid to magnesium hydroxide which generates no toxic gases and raises no problem with respect to toxicity when it is used as an additive.
A method of imparting flame retardant properties to thermoplastic resins or elastomers by blending them with magnesium hydroxide is previously known, and it is also known that the flame retardancy of the compositions can be improved by blending them with carbon black (Japanese Patent Laid-Open No. 46341/1976).
However, a large amount of magnesium hydroxide is required for imparting sufficient flame retardancy, and, consequently, this method has the disadvantage in that it is difficult to obtain compositions having satisfactory practical properties, considering that a resin composition containing a large amount of magnesium hydroxide whitens when an external force is applied thereto and exhibits low resistance to external damage.